Bicycle drive assembly

ABSTRACT

A drive assembly for a physically propelled vehicle such as a bicycle having a crank arm operatively connected to a drive member rotatively mounted on a drive axis for rotating the drive member, and a one-way clutch connecting an advance-crank arm to the crank arm for pivotal movement of the advance-crank arm relative to the crank arm in only one direction. A pedal arm is operatively connected to the connector for substantially moving a portion of a connector with an alternating motion of less than 360* in a predetermined path. A resilient spring interconnects the connector and the advance-crank arm. The connector transmits the turning force to a pivot between the connector and advancecrank arm upon application of sufficient pedal force to overcome a predetermined loading of the resilient spring, the turning force being automatically transferred from the crank arm pin to the pivot of the advance-crank arm, and being automatically transferred back to the crank arm pin upon further rotation of the crank arm and advance-crank arm as the loading of the resilient spring balances and overcomes the pedal force. When the predetermined loading of the resilient spring is overcome, a change in the angle between the connector and advance-crank arm is achieved.

United States Patent 1 Trammell, Jr.

[ Dec. 18, 1973 1 BICYCLE DRIVE ASSEMBLY [75] Inventor: Earl M.Trammell, Jr., Ladue, Mo.

[73] Assignee: Cycle-Drive Corporation, St. Louis,

[22] Filed: Feb. 28, 1972 [21] Appl. No.2 229,898

Primary Examiner-Charles J. Myhre Assistant Examiner-4 D. ShoemakerAttorney-Cohn et al.

[57] ABSTRACT A drive assembly for a physically propelled vehicle suchas a bicycle having a crank arm operatively connected to a drive memberrotatively mounted on a drive axis for rotating the drive member, and aoneway clutch connecting an advance-crank arm to the crank arm forpivotal movement of the advance-crank arm relative to the crank arm inonly one direction. A pedal arm is operatively connected to theconnector for substantially moving a portion of a connector with analternating motion of less than 360 in a predetermined path. A resilientspring interconnects the connector and the advance-crank arm. Theconnector transmits the turning force to a pivot between the connectorand advance-crank arm upon application of sufficient pedal force toovercome a predetermined loading of the resilient spring, the turningforce being automatically transferred from the crank arm pin to thepivot of the advance-crank arm, and being automatically transferred backto the crank arm pin upon further rotation of the crank arm andadvance-crank arm as the loading of the resilient spring balances andovercomes the pedal force. When the predetermined loading of theresilient spring is overcome, a change in the angle between theconnector and advance-crank arm is achieved.

17 Claims, 10 Drawing Figures PATEHTEU 1 81975 SHEET 2 OF 3 JOB Q :3 3wg JQQ BICYCLE DRIVE ASSEMBLY BACKGROUND OF THE INVENTION for propellinga bicycle with substantially reciprocating pedal action, but these priordrive assemblies have met with no success becausethey too areinefficient in their transfer of driving power through well knownratchetpawl and linkage mechanisms.

SUMMARY OF THE INVENTION This invention incorporates a pedal action incombination with a new crankstructure, that permits a more efficientapplication of pedal pressure over 360 of crank travel than does theheretofore conventional rotary pedal action bicycle or the heretoforedesigned drivemechanisms utilizing a reciprocating or oscillating pedalaction.

This new drive assembly eliminates a top dead center position fromoccurring at the top of the pedal stroke by permitting a turning forceto be applied when the crank arm is at top center position. The drivemechanism is designed so that at the moment of top center position,byapplying added pressure to the top pedal, the effective .crank armposition advances automatically from zero degrees to an establishednumber of degrees, thereby permitting a positive turning force to beapplied when the crank arm is at top center or evena few degrees beforetop center. A pedal arm is always in positionto receive a straightforward push from the riders leg. The rider can apply effective pedalpressure from approximately to 180 of each pedal power stroke. Thislever action further makes for the effective use of a high back seatwhich helps to compound the riderfs leg push.

As will be seen the resilient means onthis present drive assembly canbeadjusted in degree from a weak tension loading to a strong tensionloading. With a very weak tension loading, pedal pressure, at topcenter, would immediately be transferred to the advance-crank arm pivotmeans and so remain until pedal pressure was normally released at ornear the bottom of the stroke. With such a weak tension load setting,the angle closure between the advance-crank arm and connector is limitedby a stop or bumper on the connector which abuts the crank arm pivothead.

When the tension loading is sufficiently increased, this present driveassembly provides an accelerator thrust action that assists in attaininghigher speeds for bicycles. This accelerator thrust action isautomatically obtained at moderate to fast speeds, and occurs duringthedown pedal stroke and varies in proportion to the crank travel, whensufficient maximum pedal pressure hasbeen transferred to anadvance-crankarm position, a resilient means providing a tension loading starts toextend. When the resilient means ceases to expand, all

pedal. pressure and rate of stroke. At the moment of t pedal pressure isautomatically reversed from the ad-.

Vance-crank arm position back to the conventional crank arm position.During the early degrees of crank travel, accelerator thrust action willcause the pedal travel to accelerate in relation to conventional pedaltravel, and thenduring the middle or latter degrees of down cranktravel, it will cause the pedal to slow down in relation to conventionalpedal travel.

As will be understood, when pedaling a bicycle at.

slow speeds, the riders leg push is slower and more extended over thedown pedal travel than at fast speeds. As the speed of the bicycleincreases, the greater and quicker the leg push and the less extendedactual push there is on the down stroke, until at maximum speeds, theleg push amounts to a strong pulsating action on the pedal during theearly part of the down stroke and with little push affected over thelatter part of such stroke.

At fast speeds, it will be noted that the tensio nal loading built upinto the resilient means during the early part of the down pedal stroke,will, automatically yield a thrust action during the latter part of thedown pedal stroke. For this reason, it is believed that the improveddrive assembly will provide for the attainment of faster.

speeds for the bicycle rider.

Moreover, a pedal pressure with the present drive as sembly can be moreeffectively extended over the later degrees of the down stroke than on aconventional r0 tary type crank drive, because of the designed radius oflever action which permits the connector to remain at a favorable torqueangle to the crank arm during the later stages of the pedal stroke.

The drive assembly includes a crank armoperatively connected to a drivemember rotatively. mounted on a drive axis for rotating the drivemember, and a one-way clutch connecting an advance-crank arm to thecrank arm pin of the crank arm for pivotal movement of the.

advance-crank arm relative to the crank arm in only one direction. Apivot means secures a connector to the advance-crank arm. Pedal means isoperatively connected to the connector for substantially movinga portionof the connector with an alternatingmotion of less than 360 in apredetermined path. A resilient means interconnects the connector andthe advance crank arm. The connector transmits the pedal force to thepivot means upon application of sufficient pedal force to overcome theloading of the resilient means, the turning force being transferred fromthe crank arm pin and being advanced automatically to the pivot means toprovide an advanced, effective crank arm.

The loading of the resilient means tends to maintain a predeterminedangle between the connector and the advance-crank arm. When thepredetermined loading of the resilient means is overcome by theapplication of sufficient pedal force, the angle between the connectorand the advance-crank arm can change and permit the automatictransference of .the turning force from the crank arm pin to the pivotmeans.

The pedalmeans includes a lever pivotally mounted on a fixed axis andpivotally mounted to the connector portion,an the pedal means includes apedal arm pivotally mounted on the same fixed axis as the lever forsubstantially alternating motion of less than 360 and attached to thelever to move the lever upon movement of the pedal arm, and a pedalcarried by the pedal arm for actuating the pedal arm.

The predetermined path to which the connection portion is constrained,is offset in the direction of drive member rotation from a line drawnbetween the drive axis and the crank arm pin when the crank arm pin islocated in its top center position. This arrangement enables moreeffective transference of power by the connector to the crank arm at thelater portion of the downstroke, while the possible transference of theturning force automatically from the crank arm pin to the advanced pivotmeans provides for effective utilization of power during the earlyportion of the downstroke.

The pivot means is disposed forwardly in the direction of drive memberrotation relative to the crank arm pin and associated one-way clutchwhen the crank arm pin is located substantially at its top centerposition, whereby the effective crank arm position is automaticallyadvanced from the crank arm pin to the pivot means when the loading ofthe resilient means is overcome by the application of sufficient pedalforce.

The resilient means provides a predetermined loading that tends tomaintain the angle between the connector and the advance-crank arm untilsufficient pedal force is applied through the connector to overcome suchpredetermined loading and thereby enable a change of the angle and anautomatic transfer of the effective crank arm from the crank arm pin tothe pivot means. Preferably, the resilient means provides apredetermined tension loading that tends to maintain the included anglebetween the connector and the advance-crank arm, the resilient meansenabling a decrease in the included angle when such tension loading isovercome by sufficient pedal force.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of abicycle incorporating the improved drive assembly;

FIG. 2 is a plan view, partly in cross-section, as seen on line 2-2 ofFIG. 1;

FIG. 3 is a side elevational view of the drive assem- FIG. 4 is a topplan view of the drive assembly shown in FIG. 3;

FIG. 5 is an enlarged, cross-sectional view as seen on line 5-5 of FIG.3;

FIG. 6 is a fragmentary, cross-sectional view as seen on line 6-6 ofFIG. 5;

FIG. 7 is a schematic diagram of the drive assembly under light pedalpressure;

FIG. 8 is a schematic diagram of the drive assembly under moderate pedalpressure;

FIG. 9 is a schematic diagram of the drive assembly under heavy pedalpressure, and

FIG. 10 is a fragmentary, cross-sectional view of the spring connection.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Referring now by characters of reference to the drawing, and first toFIG. 1, it is seen that the bicycle includes a substantiallyconventional frame including a front fork l0 mounting the front wheel11, a rear fork l2 mounting the rear wheel 13, the rear fork 12 beingattached to the rear upright bar 14 that is connected at its upperportion to the front fork 10 by a cross bar 15 and at its lower portionto the front fork 10 by a diagonal bar 16. Handle bars 17 are mounted tothe front fork 10 for turning the front wheel 11. A seat 18 is carriedat the top of the rear upright bar 14. For better stroke leverage, theseat 18 includes a back rest 19.

As is best seen in FIG. 4, the diagonal bar 16 at its lower end branchesto provide opposed bar portions 20 and 21 and an intervening bar portion22 interconnected at their lower ends by a bearing journal 23. The

lower end of the rear upright bar 14 is also secured to the bearingjournal 23 as is shown in FIG. 3. From FIG. 4, it is clear that a pairof stub shafts 24 and 25 are rotatively mounted in opposite ends of thebearing journal 23. The shafts 24 and 25 define a fixed axis FA.

The opposed bar portions 20 and 21 and the intervening bar portion 22are each provided with a ball bearing 26, 28 and 27 respectively whichare transversely aligned in a co-axial'drive axis DA. Rotatively mountedby stub shaft 30 in ball bearing 26, is a sprocket 31, constituting adrive member, the sprocket 31 being located inside of the bar portion 20and being operatively connected to a smaller sprocket 32 on the rearwheel 13 by an endless chain 33 in the conventional manner. It will beunderstood that rotation of the sprocket 31 acts through the chain 33 torotate the sprocket 32 and the attached rear wheel 13.

It will be understood that the mechanism of the drive assembly actuatedby the riders right foot is the same as the mechanism provided for theriders left foot except that the component parts are appropriatelyarranged so that when the riders right foot is in its uppermostposition, the left foot is in the lowermost position. Consequently, adetailed description of the mechanism for the riders right foot willsuffice for the other mechanism and the corresponding component partswill be given identical reference numbers except that the mechanism forthe riders right foot will bear the suffix R and the mechanism for theriders left foot will bear the suffix L.

The right hand mechanism of the drive assembly includes a crank arm 34 Rpivotally mounted on the same drive axis DA as the sprocket 31. Thecrank arm 34 R includes a pair of transversely spaced arm portions 35 Rand 36 R, the crank arm portion 35 R being rotatively mounted by stubshaft 37 R in the ball bearing 28, while the crank arm portion 36 R isrotatively mounted by shaft 40 in ball bearing 27. The outer ends of thecrank arm portions 35 R and 36 R are 0peratively connected by a crankarm pin 39 R and an associated one-way clutch 41 R to an advance-crankarm 42 R disposed between the crank arm portions 35 R and 36 R. Theone-way clutch 41 R enables rotation of the advance-crank arm 42 Rrelative to the crank arm 34 R in only one direction, that directionbeing the same as the rotation of crank arm 34 R about the drive axisDA.

A connector 43 R is connected to the opposite end of the advance-crankarm 42 R by pivot means 44 R. The opposite connector end portion isconnected by a pivot means 45 R to the upper end of a lever 46 R, thelower end of the lever 46 being drivingly attached to the shaft 25 inthe bearing journal 23. Drivingly attached to the outer end of shaft 25is a pedal arm 47 R that is angularly related to the lever 46 R andextends forwardly for substantially oscillating movement about the fixedaxis FA.

Carried on the outer end of the pedal arm 47 R is a pedal 50 R adaptedto receive the riders right foot for actuating the pedal arm 47 R. Thepedal 50 R is carried by a frame 51 R that is pivoted to the outer endof the pedal arm 47 R, the frame 51 R being pivotally movable to anextended position, shown in full lines or to a retracted position shownin broken lines in FIG. 3 to selectively change the pedal position andchange the length of the torque arm from the fixed axis FA on which thepedal arm 47 R is rotatively mounted, and thereby in effect accomplish achange in driving ratio.

The lever 46 R is reciprocated by the pedal arm 47 R and transmits thepedal force through the connector 43 R to the pivot means 45 R. Thelayer 46 R constitutes a guide means that constrains the connector endportion that is connected to the lever 46 R by the pivot means 45 R to apredetermined path.

The connector 43 R includes an extended portion 52 R located on theopposite side of the pivot means 44 R from that end portion of theconnector 43 R that movable in the predetermined path. The advance-crankarm 42 R includes an extended portion 53 R located on the opposite sideof the one-way clutch 41 R from the pivot means 44 R. A spring 54 R,constituting a resil ient means, operatively extends between andinterconnects the extended portions 52 R and 53 R. This spring 54 R ispreferably closed tight under tension. When spring 54 R is locatedbetween and attached to the extended portions 52 R and 53R, itis thesame as a rigid link that prevents the included angle it between theconnector 43 R and advance-crank arm 42 R from increasing beyond apredetermined number of degrees. This spring 54 R provides apredetermined loading between the connector 43 R and the advance-crankarm 42 R which tends to maintain the predetermined, included angle d)between the connector 43 R and the advance-crank arm 42 R.

Any tendency of the connector 43 R and the advance-crank arm 42 R. torotate relatively about the pivot means 44 R to decrease the includedangle 4), will be resisted by the predetermined tension loading ofspring 54 R.

The pivot means 44 R of the connector 43 R and the advance-crank 42 R isdisposed forwardly in the direction of sprocket rotation relative to thecrank arm pin 39 R when the crank arm pin 39 R is located substantiallyat its top center position. When sufficient pedal force is appliedthrough the connector 43 R so that the tension loading of spring 54 R isovercome to allow extension of the spring 54 R and a decrease in theincluded angle 11 between the connector 43 R and the advancecrank arm 42R, all of the pedal pressure is transferred from the crank arm pin 39 Rto the advancecrank arm 42 R at the pivot means 44 R, therebyautomatically transferring and advancing the location ofthe effectivecrank arm from the crank arm pin 39 R to the pivot means 44 R. Thespring 54 R continues to expand and the included angle 42 between theconnector 43 R and the advance-crank arm 44 R continues to decreaseuntil the tension loading of the spring 54 R is balanced by the pedalforce, at which time, all the pedal force is shifted automatically backto the crank arm pin 39 R from the pivot means 44 R.

The connector 43 R normally transmits all pedal force to the crank armpin 39 R, but at the moment of sufficient pedal force to overcome thepredetermined tension loading of spring 54 R, the connector 43 Rtransfers all pedal force to the pivot means 44 R of the advance-crankarm .42 R, and upon further rotation and at the instant the spring 54 Rceases to expand, the

pedal force is automatically transmitted back to the crank arm pin 39 R.

The lever 46 moves the connector end portion attached by pivot means 45R in a predetermined path located in the direction of sprocket rotationat one side of a line drawn between the drive axis DA and the axis ofcrank arm pin 39 R when the crank arm pin 39 R is located in its topcenter position. This movement of the connector 43 enables a moreefficient transmission of force from the connector 43 R to the crank arm34 R at the later portion of the downstroke. Efficient transmission ofthe turning force by the connector 43 R is achieved at the early portionof the downstroke through the transference of pedal force to theadvanced position provided by pivot means 44 R from the crank arm pin 39R, thereby achieving an effective advanced crank arm.

The spring 54 R can be adjusted in degrees from a weak tension loadingto a strong tension loading. An adjustable screw 48 R is threadedlyattached to the inside and axially of each spring end, the screws 48 Rextending through yet secured to the extended portions 52 R and 53 R bylock nuts 49 R that are threadedly adjustable on the screws 48 R andengageable with the extended portions 52 R and 53 R. Threading thescrews 48 R into the spring 54 R reduces the effective length of thespring 54 R and thereby reduces the tension loading of the spring 54 R.The tension loading can be predetermined selectively by this adjustmentof screws 48 R.

The operation of the drive assembly is perhaps best shown by thediagrammatic illustrations of FIGS. 7 9 under various operatingconditions. FIG. 7 shows the operation under light pedal pressure. FIG.8 shows the operation under moderate pedal pressure. FIG. 9 shows theoperation under heavy pedal pressure.

FIG. 7 shows the arrangement of the components parts of the driveassembly in top center in diagram A. It will be noted that the driveaxis DA, crank arm pin 39 R and pivot means 45 R are substantiallyaligned when the crank arm pin 39 R is in the top center position at 0.In this position, the pedal arm 47 R is located in its raised limit. Thetension spring 54 R with its predetermined loading maintains theincluded angle (b be tween the connector 43 R and the advance'crank arm42 R. When light pedal pressure is applied to the pedal arm 47 R, as forexample when the bicycle is traveling down-grade, such pedal pressurewill usually not be sufficient to overcome the tension loading of spring54 R. Under these circumstances, the pedal pressure will be applied byconnector 43 R to the crank arm pin 39 R, to rotate the crank arm 34 Rand the sprocket 31.

Diagram B of FIG. '7 shows the position of the component parts of thedrive assembly at past top center under these circumstances. It will benoted that the spring 54 R has maintained its length and the includedangle between the connector 43 R and the advancecrank arm 42 R has beenmaintained constant. The one-way clutch 41 R has permittedcounterclockwise rotation of the advancecrank arm 42. R relative to thecrank arm 34 R, while the turning force applied by the connector 43 R tothe crank arm pin 39 R has turned the crank arm 34 R. in this instance,the pedal arm 47 R has moved downwardly from its raised limit in diagramA to substantially near its lower limit.

Diagram C of FIG. 7 shows the lower limit of pedal arm 47 R, with thecrank arm 34 R located at 240 past top center. Again, the turning forceis applied by the connector 43 R to the crank arm pin 39 R, the ad-Vance-crank arm 42 R continuing to rotate relatively counterclockwise tothe crank arm 34 R. The predetermined tension loading of spring 54 Rmaintains the included angle 4) between the connector 43 R and theadvance-crank arm 42 R.

As long as the pedal pressure does not overcome the tension loading ofthe spring 54 R, the included angle (b will be maintained and thecomponent parts will move in the manner described with the turning forceapplied by the connector 43 R to the crank arm pin 39 R, causingrotation of the crank arm 34 R.

FIG. 8 illustrates the operation of the drive assembly when moderatepedal pressure is applied, as for example, for propelling the bicycle onlevel or slightly upgrade. Diagram D of FIG. 8 illustrates the locationof the crank arm 34 R at past top center when sufficient force isapplied to the pedal arm 47 R to overcome the tension loading of spring54 R. The pedal arm 47 R has moved downwardly a slight distance from itsupper limit to the position shown in diagram D. It will be understoodthat the pedal force transmitted by the connector 43 R has overcome thetension loading of spring 54 R, causing the spring 54 R to extend,thereby decreasing the included angle (1) and causing an immediate andautomatic transfer of all pedal force from the crank arm pin 39 R to thepivot means 44 R between the connector 43 R and the advance-crank arm 42R. Under these conditions, the one-way clutch 41 R locks and precludesrotation of the advance-crank arm 42 R relative to the crank arm 34 Rabout the crank arm pin 39 R. The pivot means 44 R is located forwardlyof the crank arm pin 39 R in the direction of sprocket rotation.Accordingly, the effective crank arm has been advanced automaticallyseveral degrees from pin 39 R to pivot means 44 R which allows moreefficient application of the torque to the sprocket 31 by the pedalforce. When the crank arm 34 R is located at 20 past top center, andunder these conditions, the effective crank arm as determined by theposition of pivot means 44 R is located at approximately 60 past topcenter.

The spring 54 R will continue to expand until it balances the pedalforce applied through the connector 43 R to the pivot means 44 R. At theinstant the spring 54 R ceases to expand, the pedal force applied to thepivot means 44 R will be automatically and immediately transferred backto the crank arm pin 39 R, and hence the effective crank arm is shiftedback from pivot means 44 R to pin 39 R.

Diagram E of FIG. 8 illustrates the position of the component parts ofthe drive assembly after transference of the effective crank arm back tothe crank arm pin 39 R, yet the spring 54 R is still slightly extended.The pedal arm 47 R has moved downwardly a further distance and the crankarm 34 R has been rotated by the pedal force applied through theconnector 43 R to the crank arm pin 39 R. The spring 54 R continues tocontract and the included angle (11 between the connector 43 R and theadvance-crank arm 43 R continues to increase. When the pedal force issuch that it fails to overcome the predetermined loading of the spring54 R, the spring 54 R will assume its initial position as illustrated indiagram F of FIG. 8, at which time the included angle is againmaintained at its initial predetermined number of degrees. Upon furtherdownward pedal forces applied to the pedal arm 47 R, the pedal force isapplied through the connector 43 R to the effective crank arm determinedby crank arm pin 39 R.

From diagrams D, E. and F of FIG. 8, it is seen that during the earlydegrees of crank travel, the pedal arm 47 R accelerates in its downwardmovement because of the expansion of spring 54 R and the transference ofpedal force automatically from the crank arm pin 39 R to the pivot means44 R. During the middle or latter portion of the crank travel, the pedalarm 47 R will decelerate because of the contraction of the spring 54 Rand the transference of pedal force back to the crank arm pin 39 R fromthe pivot means 44 R.

FIG. 9 shows the position of the component parts of the drive assemblyunder the application of heavy pedal pressure, as for example when thebicycle is traveling up a steep grade. Upon initial application of ahigh pedal force to the pedal arm 47 R, it will again be apparent thatthe pedal force overcomes the predetermined tension loading of spring 54R and causes the spring 54 R to expand, andenable a decrease in theincluded angle 4) between the connector 43 R and the advance-crank arm42 R.

From a comparison of diagram E of FIG. 8 and diagram G of FIG. 9, itwill be understood that under the heavier pedal force, the spring 54 Ris extended further and the included angle (1) is decreased further.Again, under these conditions, the one-way clutch 41 R locks andprecludes rotation of the advance-crank arm 42 R relative to the crankarm 34 R about the crank arm pin 39 R.

Again, immediately upon application of sufficient pedal force toovercome the predetermined tension loading of spring 54 R, the pedalforce transmitted by connector 43 R is transferred automatically andimmediately from the crank arm pin 39 R to the pivot means 44 R, therebyadvancing the effective crank arm several degrees. For example, indiagram G of FIG. 9, under these operating conditions, when the crankarm 34 R is located at 45 past top center, the pivot means 44 R, andhence the effective crank arm, is located at just under past top center.

When the tension loading of spring 54 R balances the pedal force, thepedal force transmitted by the connector 43 R will be automatically andimmediately transferred back to the crank arm pin 39 R from the pivotmeans 44 R, and hence the effective crank arm is shifted back from pivotmeans 44 R to pin 39 R. Then, the spring 54 R will contract and theincluded angle (1) is allowed to increase. In diagram H of FIG. 9, itwill be seen that the spring 54 R has contracted slightly from itsextended length as shown in diagram G, that the included angle d hasincreased, and that the advancecrank arm 43 R has rotatedcounterclockwise about crank arm pin 39 R relative to the crank arm 34 Ras permitted by one-way clutch 41 R.

Diagram I of FIG. 9 illustrates the position of the component parts uponfurther downward travel of the pedal arm 47 R and rotation of the crankarm 34 R. In this position, when the crank arm 34 R is at past topcenter, the spring 54 R has assumed its initial position and theincluded angle 45 has assumed its initial predetermined number ofdegrees. The pedal force transmitted by the connector 43 R is applied tothe effective crank arm determined by crank arm pin 39 R.

With a very weak tension loading, as determined by selective adjustmentof screws 48 R into the spring 54 R and the locking of the screws 48 Rin such position by the nuts 49 R, pedal pressure at top center would beimmediately transferred to the advance-crank arm pivot means 44 R and soremainuntil the pedal pressure was normally released at or near thebottom of the pedal stroke. With such a weak tension load setting, theangle d) closure between the advance-crank arm 42 R and connector 43 Ris limited by a stop 57 R on the connector 43 R which abuts the crankarm pivot head.

I claim as my invention:

1. A drive assembly for a physically-propelled vehicle, comprising:

a. a drive rotatively mounted on a drive axis,

b. a crank arm mounted for rotation about the drive axis and operativelyconnected to the drive member for rotating the drive member,

c. an advance-crank arm,

d. a connector pivotally connected to the advancecrank arm,

e. pedal means operatively connected to the connector for moving theconnector with an alternating motion of less than 360 in a predeterminedpath, and

f. means, during application of pedal force, for automatically shiftingthe pedal force from the crank arm to the advance-crank arm, and forlater reversing this action during the rotation of the crank arm andadvance-crank arm about the drive axis.

2. A drive assembly for a physically-propelled vehicle, comprising:

a. a drive member rotatively mounted on a drive axis,

12. a crank arm operatively connected to the drive member for rotatingthe drive member,

c. a crank arm pin carried by the crank arm,

d. an advance-crank arm,

2. clutch means associated with the crank arm pin connecting theadvance-crank arm to the crank arm for relative pivotal movement in onlyone direction,

f. a connector,

g. pivot means pivotally connecting the connector to the advance-crankarm,

h. pedal means operatively connected to the connector for moving aportion of the connector with an alternating motion of less than 360 ina predetermined path,

i. resilient means interconnecting the connector and the advance-crankarm, and

jthe connector transferring the turning force from the crank arm pin tothe pivot means upon application of sufficient pedal force to overcomethe loading of the resilient means.

3. a drive assembly as defined in claim 2, in which:

k. the crank arm pin is located in spaced relation to i the drive axis,

1. the pivot means is in spaced relation to the crank arm pin, and

m. all turning force is transferred from the crank arm pin andtransmitted by the connector to the pivot means upon application ofsufficient pedal force to overcome the loading of the resilient meansand enable a change in the angle between the connector and advance-crankarm.

4. A drive assembly as defined in claim 2, in which:

k. the pedal means includes:

l. a pivotally mounted pedal arm I. a pedal frame carries the pedal andis mounted on the pedal arm for selective movement to locations atdifferent distances from the fixed axis to change the torque l0 arm.

6. A drive assembly as defined in claim 3, in which:

n. the clutch means precludes rotation of the ad- Vance-crank armrelative to the crank arm in the same direction as the crank armrotation about the drive axis.

7. A drive assembly as defined in claim 3, in which:

n. the pedal means is mounted for substantially alternating motion ofless that 360. 8. A drive assembly as defined in claim 6, in which: 0.the pedal means moves the said connector portion in the predeterminedpath that is located offset forwardly in the direction of drive memberrotation from a line interconnecting the drive axis and top center ofthe crank arm pin. 9. A drive assembly as defined in claim 3, in which:n. the pivot means is disposed forwardly in the direc tion of drivemember rotation relative to the crank arm pin when the crank arm pin islocated substantially at its top center position, whereby the effectivecrank arm position is automatically advanced from the crank arm pin tothe said pivot means when the loading of the resilient means is overcomeby the application of sufficient pedal force. 10. A drive assembly asdefined in claim 3, in which: n. the clutch means precludes relativerotation of the crank arm and advance-crank arm in the same direction asthe crank arm rotation about the drive axis, 0. the pedal is mounted foralternating motion of less than 360, and p. the pivot means is disposedforwardly in the direction of drive member rotation. relative to thecrank arm pin when the crank arm pin is located substantially at its topcenter position, whereby the effective crank arm position isautomatically advanced from the crank arm pin to the said pivot meanswhen the loading of the resilient means is overcome by the applicationof sufficient pedal force. 11. A drive assembly as defined in claim 10,in which: g. the pedal means includes:

1. a pedal arm pivotally mounted on a fixed axis for substantiallyalternating motion of less than 360, 2. a pedal carried by the pedal armfor actuating the pedal arm, and 3. means connecting the connector tothe pedal arm for actuating thev connector. 12. A drive assembly asdefined in claim 3, in which: n. the resilient means provides apredetermined loading that maintains the angle between the connector andthe advance-crank arm until sufficient pedal force is applied throughthe connector to overcome the predetermined loading of the resilientmeans and thereby enable the change of the angle and an automatictransfer of the effective crank arm position from the crank arm pin tothe pivot means. 13. A drive assembly as defined in claim 12, in which:

0. the resilient means is under predetermined tension loading that tendsto maintain the included angle between the connector and theadvance-crank arm.

14. A drive assembly as defined in claim 12, in which:

' 0. the connector includes an extended portion located on the oppositeside of the pivot means from that portion of the connector movable inthe predetermined path,

p. the advance-crank arm includes an extended portion located on theopposite side of the crank arm pin from the said pivot means, and

q. the resilient means operatively extends between and interconnects thesaid-extended portions of the connector and advance-crank arm.

15. A drive assembly as defined in claim 14, in which:

r. the resilient means is a tension spring, and

s. screws threadedly engage the ends of the spring and connect thespring to the extended portions, the screws being adjustable topredetermine the effective tensional loading of the spring.

16. A drive assembly as defined in claim 14, in which:

r. the pivot means is disposed forwardly in the direction of drivemember rotation relative to the crank arm pin when the crank arm pin islocated substantially at its top center position, whereby the effectivecrank arm is automatically advanced from the I crank arm pin to the saidpivot means when the loading of the resilient means is overcome by theapplication of sufficient pedal force.

17. A drive assembly for a physically-propelled vehicle, comprising:

a. a drive member rotatively mounted on a drive axis,

b. a crank arm mounted for rotation about the drive axis and operativelyconnected to the drive member for rotating the drive member,

0. a crank arm pin carried by the crank arm,

11. an advance-crank arm,

e. a one-way clutch associated with the crank arm pin and connecting theadvance-crank arm to the crank arm in spaced relation to the drive axisfor permitting pivotal movement of the advance-crank arm about the crankarm pin and relative to the crank arm in only one direction,

f. a connector,

g. a pivot means between the connector and the ad- Vance-crank arm inspaced relation to the crank arm pin,

h. a lever pivotally mounted on a fixed axis and pivotally connected tothe connector for moving a portion of the connector in a predeterminedpath offset in the direction of drive member rotation from a lineinterconnecting the drive axis and crank arm pin when the crank arm pinis located in its top center position,

i. a pedal arm pivotally mounted for substantially alternating motion ofless than 360 on the same fixed axis as the lever, the pedal arm beingattached to the lever to move the lever upon movement of the pedal arm,

j. a pedal carried by the pedal arm for actuating the pedal arm,

k. the connector including an extended portion located on the oppositeside of the pivot means from that portion of the connector movable inthe predetermined path,

I. the advance-crank arm including an extended portion located on theopposite side of the crank arm pin from the said pivot means,

m. a resilient means under a predetermined tension loading extendingbetween and interconnecting the said extended portions of the connectorand the advance-crank arm, the resilient means tending to maintain theincluded angle between the connector and the advance-crank arm, and

n. the connector transmitting all of the turning force to the pivotmeans upon application of sufficient force to the pedal to overcome thepredetermined tension loading and increase the tension loading of theresilient means and enable a change in the included angle between theconnector and the advance-crank arm, all of the turning force beingautomatically shifted from the crank arm pin to the pivot means, andbeing automatically shifted back to the crank arm pin during furtherrotation of the crank arm and advance-crank arm about the drive axis asthe loading of the resilient means is substantially balanced by thepedal force.

1. A drive assembly for a physically-propelled vehicle, comprising: a. adrive rotatively mounted on a drive axis, b. a crank arm mounted forrotation about the drive axis and operatively connected to the drivemember for rotating the drive member, c. an advance-crank arm, d. aconnector pivotally connected to the advance-crank arm, e. pedal meansoperatively connected to the connector for moving the connector with analternating motion of less than 360* in a predetermined path, and f.means, during application of pedal force, for automatically shifting thepedal force from the crank arm to the advancecrank arm, and for laterreversing this action during the rotation of the crank arm andadvance-crank arm about the drive axis.
 2. A drive assembly for aphysically-propelled vehicle, comprising: a. a drive member rotativelymounted on a drive axis, b. a crank arm operatively connected to thedrive member for rotating the drive member, c. a crank arm pin carriedby the crank arm, d. an advance-crank arm, e. clutch means associatedwith the crank arm pin connecting the advance-crank arm to the crank armfor relative pivotal movement in only one direction, f. a connector, g.pivot means pivotally connecting the connector to the advance-crank arm,h. pedal means operatively connected to the connector for moving aportion of the connector with an alternating motion of less than 360* ina predetermined path, i. resilient means interconnecting the connectorand the advance-crank arm, and j. the connector transferring the turningforce from the crank arm pin to the pivot means upon application ofsufficient pedal force to overcome the loading of the resilient means.2. means connecting the said connector to the pedal arm to actuate theconnector upon movement of the pedal arm, and
 2. a pedal carried by thepedal arm for actuating the pedal arm, and
 3. means connecting theconnector to the pedal arm for actuating the connector.
 3. a pedalcarried by the pedal arm for actuating the pedal arm.
 3. a driveassembly as defined in claim 2, in which: k. the crank arm pin islocated in spaced relation to the drive axis, l. the pivot means is inspaced relation to the crank arm pin, and m. all turning force istransferred from the crank arm pin and transmitted by the connector tothe pivot means upon application of sufficient pedal force to overcomethe loading of the resilient means and enable a change in the anglebetween the connector and advance-crank arm.
 4. A drive assembly asdefined in claim 2, in which: k. the pedal means includes:
 5. A driveassembly as defined in claim 4, in which: l. a pedal frame carries thepedal and is mounted on the pedal arm for selective movement tolocations at different distances from the fixed axis to change thetorque arm.
 6. A drive assembly as defined in claim 3, in which: n. theclutch means precludes rotation of the advance-crank arm relative to thecrank arm in the same direction as the crank arm rotation about thedrive axis.
 7. A drive assembly as defined in claim 3, in which: n. thepedal means is mounted for substantially alternating motion of less that360*.
 8. A drive assembly as defined in claim 6, in which: o. the pedalmeans moves the said connector portion in the predetermined path that islocated offset forwardly in the direction of drive member rotation froma line interconnecting the drive axis and top center of the crank armpin.
 9. A drive assembly as defined in claim 3, in which: n. the pivotmeans is disposed forwardly in the direction of drive member rotationrelative to the crank arm pin when the crank arm pin is locatedsubstantially at its top center position, whereby the effective crankarm position is automatically advanced from the crank arm pin to thesaid pivot means when the loading of the resilient means is overcome bythe application of sufficient pedal force.
 10. A drive assembly asdefined in claim 3, in which: n. the clutch means precludes relativerotation of the crank arm and advance-crank arm in the same direction asthe crank arm rotation about the drive axis, o. the pedal is mounted foralternating motion of less than 360*, and p. the pivot means is disposedforwardly in the direction of drive member rotation relative to thecrank arm pin when the crank arm pin is located substantially at its topcenter position, whereby the effective crank arm position isautomatically advanced from the crank arm pin to the said pivot meanswhen the loading of the resilient means is overcome by the applicationof sufficient pedal force.
 11. A drive assembly as defined in claim 10,in which: g. the pedal means includes:
 12. A drive assembly as definedin claim 3, in which: n. the resilient means provides a predeterminedloading that maintains the angle between the connector and theadvance-crank arm until sufficient pedal force is applied through theconnector to overcome the predetermined loading of the resilient meansand thereby enable the change of the angle and an automatic transfer ofthe effective crank arm position from the crank arm pin to the pivotmeans.
 13. A drive assembly as defined in claim 12, in which: o. theresilient means is under predetermined tension loading that tends tomaintain the included angle between the connector and the advance-crankarm.
 14. A drive assembly as defined in claim 12, in which: o. theconnector includes an extended portion located on the opposite side ofthe pivot means from that portion of the connector movable in thepredetermined path, p. the advance-crank arm includes an extendedportion located on the opposite side of the crank arm pin from the saidpivot means, and q. the resilient means operatively extends between andinterconnects the said extended portions of the connector andadvance-crank arm.
 15. A drive assembly as defined in claim 14, inwhich: r. the resilient means is a tension spring, and s. screwsthreadedly engage the ends of the spring and connect the spring to theextended portions, the screws being adjustable to predetermine theeffective tensional loading of the spring.
 16. A drive assembly asdefined in claim 14, in which: r. the pivot means is disposed forwardlyin the direction of drive member rotation relative to the crank arm pinwhen the crank arm pin is located substantially at its top centerposition, whereby the effective crank arm is automatically advanced fromthe crank arm pin to the said pivot means when the loading of theresilient means is overcome by the application of sufficient pedalforce.
 17. A drive assembly for a physically-propelled vehicle,comprising: a. a drive member rotatively mounted on a drive axis, b. acrank arm mounted for rotation about the drive axis and operativelyconnected to the drive member for rotating the drive member, c. a crankarm pin carried by the crank arm, d. an advance-crank arm, e. a one-wayclutch associated with the crank arm pin and connecting theadvance-crank arm to the crank arm in spaced relation to the drive axisfor permitting pivotal movement of the advance-crank arm about the crankarm pin and relative to the crank arm in only one direction, f. aconnector, g. a pivot means between the connector and the advance-crankarm in spaced relation to the crank arm pin, h. a lever pivotallymounted on a fixed axis and pivotally connected to the connector formoving a portion of the connector in a predetermined path offset in thedirection of drive member rotation from a line interconnecting the driveaxis and crank arm pin when the crank arm pin is located in its topcenter position, i. a pedal arm pivotally mounted for substantiallyalternating motion of less than 360* on the same fixed axis as thelever, the pedal arm being attached to the lever to move the lever uponmovement of the pedal arm, j. a pedal carried by the pedal arm foractuating the pedal arm, k. the connector including an extended portionlocated on the opposite side of the pivot means from that portion of theconnector movable in the predetermined path, l. the advance-crank armincluding an extended portion located on the opposite side of the crankarm pin from the said pivot means, m. a resilient means under apredetermined tension loading extending between and interconnecting thesaid extended portions of the connector and the advance-crank arm, theresilient means tending to maintain the included angle between theconnector and the advance-crank arm, and n. the connector transmittingall of the turning force to the pivot means upon application ofsufficient force to the pedal to overcome the predetermined tensionloading and increase the tension loading of the resilient means andenable a change in the included angle between the connector and theadvance-crank arm, all of the turning force being automatically shiftedfrom the crank arm pin to the pivot means, and being automaticallyshifted back to the crank arm pin during further rotation of the crankarm and advance-crank arm about the drive axis as the loading of theresilient means is substantially balanced by the pedal force.